Tools and technology of radical and level drilling/well completion under ultra-short radius

ABSTRACT

The invention relates to a field of extracting petroleum, particularly to tools and technology of radical and level drilling/well completion under ultra-short radius. The tools of the invention are involved with a deflecting drill tool and level drill tool. The deflecting drill tool consists of a deflecting rotary assembly, flexible drill pipe, directional follow-up tube, tail tube for deflecting drill tool, and drill pipe nipple joints; The level tool consists of a level rotary assembly, the flexible drill pipe, quick couplings, the directional follow-up tube, a tail tube for level drill tool, the drill pipe nipple joint, an adjusting nipple joint, a recessed left hand thread bushing, and convex left hand thread coupling and characterized in that: a triangle backing block is installed on outside of a casing of the deflecting rotary assembly. Rear end of the deflecting rotary assembly is connected with the flexible drill pipe by means of nuts. Splines matched with each other are provided at the level rotary assembly and the flexible drill pipe. The tail tube for level drill tool has a recessed left hand thread bushing and convex left hand thread coupling; Each of the flexible drill pipe is 140˜150 mm long. An external spline is set at the front of an inner ball and an internal spline is installed on the main body of the flexible drill pipe fixing tight with the nut. A body of the inner ball is situated in a ball bowl and in frontal part of the main body of the flexible drill pipe. Any single section of the flexible drill pipe may bend 3°-6° spacing between slots is 100-110 mm, width of the slot is 3.5-4 mm. This invention is featured level drilling under ultra-short radius with more accurate drilling, more convenient service and easier assembling. It is not only time and labor saving but also easy and convenient in service when the invention is adopted. The invention can be applied in fields of oil extraction, gas and running water.

FIELD OF THE INVENTION

The invention relates to a field of extracting petroleum, particularlyto a special drilling tool and oil extraction technology, namely, thetools and technology of radical and level drilling/well completion underultra-short radius.

BACKGROUND OF THE INVENTION

Although R&D work on an ultra-short radius level drilling tools hasgained a lot of results, there are still many hard nuts remaining to betackled. In drilling work for inclined interval and level interval, samekind of drilling tools are being used at present. During level intervaldrilling after finishing inclined interval, an orientation is difficultto be controlled, easy to cause deviation. The earlier developeddrilling tools have the shortcoming that structuring members of flexibledrill pipe are fixed up or connected together by way of clasping andwelding, which leads to being difficult in assembling and time-consumingin service. Besides, drilling fluid is being delivered in a way ofnormal circulation in drilling process, which is easy to bring about“sand sticking” and to lower working efficiency.

SUMMARY OF THE INVENTION

For overcoming the technical problems mentioned above, the purpose ofthe invention is to introduce a new technology together with a new setof special drilling tools consisting respectively of deflecting andlevel drilling tools purpose ones. This new technology and related newtools are featured with more accurate drilling, more convenient serviceand easier assembling. The structuring members of its flexible drillpipes are fitted together with external and internal splines andmatching nuts, resulting in more convenient assembling and service. Whatis more, drilling fluid is being delivered in a way of reversecirculation in drilling process, which avoids, effectively, “sandsticking” so as to improve working efficiency very much.

The ultra-short radius radial and level drilling and well completingtools are involved with a deflecting drill tool and level drill tool.The deflecting drill tool consists of a deflecting rotary assembly,flexible drill pipe, directional follow-up tube, tail tube fordeflecting drill tool, and drill pipe nipple joints; the level toolconsists of a level rotary assembly, the flexible drill pipe, quickcouplings, the directional follow-up tube, a tail tube for level drilltool, the drill pipe nipple joint, an adjusting nipple joint, a recessedleft hand thread bushing, and convex left hand thread coupling andcharacterized in that:

a) The deflecting rotary assembly has a deflecting drill bit installedon front end of its central shaft, on which besides relevantcentralizing bearing and pressure bearing, have a collar and felt washerassemblage, with a triangle backing block outside of a casing; Rear endof the deflecting rotary assembly is connected with the flexible drillpipe by means of nuts and by way of main body of flexible drill pipe;The level rotary assembly has a level drill bit installed on front endof its horizontal shaft, the rear end of the level rotary assemblyhaving an internal spline connected with the quick coupling, and acentralizing bearing and the pressure bearing, collar and felt washerassemblage are set inside of a casing, a rectangle backing block is setoutside of the casing.

b) The flexible drill pipe is made up of several single sections each ofwhich is 140˜150 mm long and consisting of five parts; at front end ofan inner ball there is a cylindrical shaped tail with the externalspline; and there is the internal spline on the main body of theflexible drill pipe; the external spline and internal spline are matchedthrough the nut tightening; a ball body of the inner ball, surroundedwith steel balls, is located inside a ball bowl and at front part of themain body of the flexible drill pipe; the ball bowl and the main body ofthe flexible drill pipe are threaded tight by covering; last section ofthe flexible drill pipe is integrally united with the adjusting nipplejoint through the nut tightening.

c) The quick couplings match mutually; the quick coupling is united witha tail of the horizontal shaft integrally through the nut tightening;the quick couplings have a central tube, the external spline andinternal spline respectively and also its gasket and gland.

d) The directional follow-up tube is made of a slotted seamless steelpipe; over the slotted pipe, bending angle banking stops are installed,with 6-8 mm thick and 70-75 wide, and cover plates are situated abovebending angle banking stops for restricting lateral movement of bendingangle banking stops; space between slots is 100-110 mm, width of theslot is 3.5-4 mm and at lower part of the pipe there has left a 50-70 mmwidth of pipe wall to serve as rib.

e) There are two kinds of tail tubes, one is tail tube for thedeflecting drill tool, another is tail tube for the level drill tool,wherein a right hand thread bushing is connected to a straight tube bymeans of a right hand thread coupling; recessed left hand thread bushingis connected to a straight tube by means of a left hand thread coupling.

The Technologies of Radial and Level Drilling and Well Completion UnderUltra-Short Radius, Characterized in that:

a) Cut a window on a well pipe wall at designed depth by using awhip-stock and milling cone firstly.

b) Inclined drilling: To fix the deflecting rotary assembly onto frontend of the directional follow-up tube connected the tail tube fordeflecting drill tool; After putting the flexible drill pipe into thedirectional follow-up tube and connect the flexible drill pipe withcentral shaft of the deflecting rotary assembly, then to sink theassembled body into a well; Under functioning of the whip-stock, a drillbit moves out of the well pipe wall, from the window slot, to keepperforming inclined drilling until designed footage is reached, theinclined drilling tool is lift then;

c) Level drilling: To fix the level rotary assembly onto front end ofthe directional follow-up tube connected the tail tube for level drilltool; To put the flexible drill pipe having the quick coupling at itsfront end, into the directional follow-up tube. The adjusting nipplejoint and the drill pipe are connected at a tail of the flexible drillpipe by using a patching of flexible drill pipe; After being matchedwith each other, the convex left hand thread coupling and the recessedleft hand thread bushing are connected to the adjusting nipple joint byway of screwing, then sink the assembled body into well after connectionby using the recessed left hand thread bushing and the convex left handthread coupling. The flexible drill pipe transmits torque to the leveldrill bit and drives it to perform level drilling, the directionalfollow-up tube follows up until designed footage is reached; Upon endingof drilling work, remove the quick couplings by reversing it for half aturn and then lift the flexible drill pipe to such an extent that theconvex left hand thread coupling is lifted to the recessed left handbushing of tail tube; turn the drill pipe forward so that the recessedleft hand thread bushing is separated from the left hand threadcoupling; Lift the flexible drill pipe out of the well and leave thedirectional follow-up tube and the level rotary assembly in levelinterval and the tail tube for level drill tool in straight hole;

d) Finishing well completion work after lead seal setting.

An included angle of 2°-3° is formed between the deflecting drill bitand the directional follow-up tube in the same bending direction due tothe triangle backing block installed on outside of the casing of thedeflecting rotary assembly; The central shaft is raised by means of therectangle backing block installed on outside of the casing of the levelrotary assembly, so that the level drill bit may work in leveldirection. The external spline and internal spline and nuts are used forconnecting sections of the flexible drill pipe and any single section ofthe flexible drill pipe may bend 3°-6°; the flexible drill pipe may berotated within the range of 360°, each meter of the flexible drill pipeto bend is 18˜22°. Drilling fluid is conveyed in drilling process,through the annular space formed between the well pipe wall and theflexible drill pipe and then is returned to ground along a drill bithole and a central hole of flexible drill pipe, namely, drilling fluidis conveyed in away of reverse circulation; When designed drilling depthis reached, the flexible drill pipe has to be separated from the levelrotary assembly via the quick coupling; To lift the flexible drill pipeto such an extent that the convex left hand coupling is up to therecessed left hand bushing of the tail tube; Turn the flexible drillpipe forward so that the recessed left hand thread bushing is separatedfrom the convex left hand thread coupling; Then lift the flexible drillpipe out of well and leave the directional follow-up tube and the levelrotary assembly in the level interval and tail tube for level drill toolin the straight hole; Finally, accomplish the work of well completionafter lead seal setting.

The Advantages of the Invention are Summarized as Follows:

1. For conventional flexible drill pipes, their parts and components arefixed and connected with welding technology. In this invention a newtechnology for part and component fixing and connection is introducedfor making flexible drill pipes—by means of splines and threading. Thistechnology is not only time and labor saving but also easy andconvenient in service.

2. Conventional directional follow-up tube is made up of trapezoidalshaped short pipe welded on a steel plate. New technology is adopted inthe invention by making slotted seamless steel pipe and 50-70 mm widthof tube wall left at lower part, serving as rib, which enhancingintensity of parts and saving spaces.

3. For conventional technology, deflecting process is proceeded attarget zone, 2-3 m of casing wall has to be cut off before utilizingwhip-stock to exercise deflecting. Only a 1-1.3 m width of window in thepresent invention has to be cut on casing wall before deflectingoperation so that reducing site work difficulty a lot and saving sitework time for 2-3 days as well as less damage to casing wall andincreasing its strength.

4. For conventional technology, drilling fluid is conveyed in a way ofpositive circulation. This invention adopts reverse circulation processfor conveying drilling fluid, which has the advantages of thoroughremoving of rock cuttings to ensure more accurate drilling. Sincedrilling fluid is delivered between the flexible drill pipe and wellwall and returned to ground along holes of drill bit and the flexibledrill pipe, “sand sticking” phenomenon is avoided and work efficiencyincreased.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic drawing of the deflected drilling tool assembling;

FIG. 2 is a schematic drawing of the horizontal drilling toolassembling;

FIG. 3 is a schematic drawing of assembling structure of the deflectingrotary assembly (1) in FIG. 1;

FIG. 4 is a schematic drawing of assembling structure of the levelrotary assembly (2) in FIG. 2;

FIG. 5 is a schematic drawing of assembling structure of the flexibledrill pipe (3);

FIG. 6 is a schematic drawing of assembling structure of the directionalfollow-up tube (4);

FIG. 7 is a top view of the FIG. 6;

FIG. 8 is a cut-open view in direction A of the FIG. 7;

FIG. 9 is a schematic drawing of a structure of the tail tube (5) fordeflecting drill tool;

FIG. 10 is a schematic drawing of a structure of the tail tube (5′) forthe level drill tool;

FIG. 11 is a schematic drawing of the drill pipe nipple joint (6);

FIG. 12 is a schematic drawing of the adjusting nipple joint (7);

FIG. 13 is a drawing of the convex left hand thread coupling (8)'sstructure;

FIG. 14 is a break-down drawing of a single section of the nipple jointof flexible drill pipe (3);

FIG. 15 is a assembling drawing of single section of the nipple joint offlexible drill pipe (3);

FIG. 16 is a schematic drawing of the quick coupling (9′)'s structure;

FIG. 17 is a schematic drawing of the quick coupling (9)'s structure.

Wherein, 1. deflecting rotary assembly; 2. level rotary assembly; 3.flexible drill pipe; 4. directional follow-up tube; 5. tail tube fordeflecting drill tool; 5′. tail tube for level drill tool; 6. nipplejoint of flexible drill pipe; 7. adjusting nipple joint; 8. convex lefthand thread coupling; 8′. recessed left hand thread bushing; 9 & 9′.quick couplings; 11. deflecting drill bit; 12. central shaft; 13.collar; 14. centralizing bearing; 15. backing block; 16. pressurebearing; 17. felt washer; 18. casing; 21. level drill bit; 22.horizontal shaft; 23. centralizing bearing; 24. backing block; 25.casing; 31. inner ball; 31′. steel ball; 32. nut; 33. bowl; 34.covering; 35. bearing; 36. main body of the flexible drill pipe; 37.O-ring; 38. patching of flexible drill pipe; 39. external spline; 39′.internal spline; 41. coupling; 42. bending angle banking stop; 43. coverplate; 44. slotted steel pipe; 45. rib; 51. right hand thread bushing;52. right hand threaded coupling; 53 & 53′. straight tube; 91. gasket;92. gland; 93. central tube; A-A showing cut open view.

DETAILED DESCRIPTION OF THE INVENTION

The tool and the process and principle of extracting petroleum providedby the present invention are described in details associated with Figsbelow.

Example 1 1. Assembling of Various Tools of the Present Invention

(1) Fixing of the deflecting rotary assembly 1, firstly. As shown inFIG. 3, fit, one after another, the centralizing bearing 14, thepressure bearing 16, the collar 13 (for sealing), and the felt washer 17into the casing 18 and then put then onto the central shaft 12. Connectthe deflecting drill bit 11 to front end of the central shaft 12 by wayof threading, weld triangle backing block 15 onto out surface of thecasing 18, and then weld the resulting deflecting rotary assembly 1 ontofront end of the directional follow-up tube 4.

(2) Fixing of the level rotary assembly 2. As shown in FIG. 4, fit, oneafter another, the centralizing bearing 14, the pressure bearing 16,collar 13, and the felt washer 17 into the casing 25 and then put themonto the central shaft 22. Connect the level drill bit 21 to front endof the horizontal shaft 22 by way of threading, weld rectangle backingblock 24 onto out surface of the casing 25. Opposite joint together theinternal spline 39′ of quick coupling and external spline 39 of centralshaft and then fix jointed the internal spline 39′ and external spline39 by way of threading. Weld the resulting level rotary assembly 2 ontofront end of the directional follow-up tube 4.

(3) Fixing of the flexible drill pipe 3. As shown in FIG. 5, theflexible drill pipe 3 is composed of several single sections connectedwith each other, and each single section is 140 mm long, in thisexample, total length of the flexible drill pipe is 14.0 m. A singlesection is comprised of the inner ball 31, the nut 32, the bowl 33; thecovering 34 and the main body of the flexible drill pipe 36 five parts.As shown in FIGS. 14 and 15, the external spline 39 is installed oncylindrical shaped tail of the inner ball 31 at its front end and theinternal spline 39′ is installed on the main body of the flexible drillpipe 36. Matched the external spline 39′ and the internal spline 39 arecombined tight with the nut 32. A body of the inner ball 31 is situatedin the ball bowl 33 and in frontal part of the main body of the flexibledrill pipe 36, with steel balls 31′ surrounded, and the ball bowl 33 andthe main body of the flexible drill pipe 36 are fixed by the covering34. Last section of the flexible drill pipe and the adjusting nipplejoint 7 are integrally connected by the nut 32. An O-ring 37 sealed upby placing in between. Bearings 35, located between the main body of theflexible drill pipe 36 and the directional follow-up tube 4, arefunctioning to reduce frictions between the flexible drill pipe and thedirectional follow-up tube. Sections are connected by means of theexternal spline 39 and the internal spline 39′ and the nut 32. Splinesare functioning to transmit torque and the nut 32, to fix them tight. Asingle section of the flexible drill pipe may bend 3°-6°, based on theposition of neighboring one, so that the flexible drill pipe may rotateand transmit torque within 360° to drive the level drill bit 21 to workvia connection of the quick coupling 9′ at front end of the flexibledrill pipe 3 and quick coupling 9 at rear end of the level rotaryassembly. The inner balls are to be made of 40#Cr—Mn—Mo and the steelballs 31′ are of bearing steel.

(4) Fixing of the directional follow-up tube 4. As shown in FIG. 6, thedirectional follow-up tube is made of a slotted seamless tube. On top ofthe slotted seamless tube 44 there is welded bending angle banking stop42 made of 25#steel, 6 mm thick and 25 mm wide, over which is the coverplate 43 functioning to limit its lateral movement. At lower part ofsteel pipe there is left a wall width of 50˜70 mm to serve as rib 45.The bending angle banking stop restricts openness of steel pipe slots.The directional follow-up tube adopts a 108 mm diameter seamless steeltube having 3.5 wide slots with a spacing of 100 mm between slots. Widthof slot, spacing distance between slots and rib width at lower part ofsteel pipe are all fixed values, and there are the bending angle bankingstops for slots to restrict orientation and bending angle of directionalfollow-up tube according to the designed requirement.

(5) Fixing of tail tube. As shown in FIGS. 9 and 10, there are two typesof tail tubes, one is tail tube 5 for the deflecting drill tool,another, tail tube 5′ for the level drill tool. One end of the tail tube5 for the deflecting drill tool is thread connected tight to thestraight pipe 53 by means of the right hand thread bushing 51 and theright hand thread coupling 52, another end of it further connected totail of the directional follow-up tube through the coupling 41. One endof the drill tool 5′ for level drill tool tightly connected to thestraight pipe 53′ via the recessed left hand thread bushing 8′ and theconvex left hand thread coupling 8 in a way of left hand threading.Another end of it connected to the directional follow-up tube 4 via thecoupling 41 by way of left hand threading.

2. Depending on Particular Process and their Working Principles, theseDrilling Tools have to be Operated in Ways of the Following

Step 1, a window of 1.0 m length has to be cut on wall of well pipe atthe designed depth with the aid of hanging whip-stock and milling cone.

Step 2, inclined Drilling. Sink the directional follow-up tube 4, whichis weld connected with the deflecting rotary assembly 1 at its front endand connected with the tail tube 5 for deflecting drill tool at rear endvia the coupling 41, into well and hang it at well mouth by means of alift sub. Fit the flexible drill pipe 3 into the directional follow-uptube 4 and then connect it with the central shaft 12 of deflectingrotary assembly through the nut 32. Tail of the patching of flexibledrill pipe 38 is thread connected to the nipple joint of flexible drillpipe 6 having the right hand thread coupling 51. Connect the right handthread bushing 51 to the right hand thread coupling 52 at end of tailtube 5 for deflecting drill tool, and to install a centralizer andconventional drill pipe to the nipple joint of flexible drill pipe 6?,then to sink integrated assemblage into well. The Under the function ofthe whip-stock, the deflecting rotary assembly 1 and deflecting drillbit 11 go through cut window on well pipe wall and move out of it toperform inclined drilling to level direction, until designed footage isreached. Each group of inner balls may bend 3°-6°, based on the positionof neighboring one, and each meter of the flexible drill pipe may bend20°, based on the position of neighboring one. Deflecting angle is 90°;inclined drilling speed=90°/20°=4.5 m, namely, when drilling at 4.5 m,curvature radius R=Circumference/(2p)=inclined drillingspeed*4/(2p)=4.5*4/(2p)=2.87 m. After finishing inclined drilling, thedeflecting drill tool is lift out of well.

Step 3, Level Drilling. Sink the directional follow-up tube 4, which isweld connected with the level rotary assembly 2 at its front end andconnected with the tail tube 5′ for level drill tool at its rear end viathe coupling 41, into well and hang the assembled body at well mouth bymeans of the lift sub. Fit the flexible drill pipe 3 having the quickcoupling 9′ at its front end into the directional follow-up tube 4, andthen threading connect tail of the patching of flexible drill pipe 38,the adjusting nipple joint 7 and the convex left hand thread coupling 8.The nipple joint of flexible drill pipe 6 sleeved with the recessed lefthand thread bushing 8′ is threaded on to the convex left hand threadcoupling 8 resulting in the recessed left hand thread bushing 8′connected with the convex left hand thread coupling 8 at the end of thetail tube 5′ for level drill tool. Since the outside dimension of convexcoupling is greater than the inner diameter of the recessed left handthread bushing 8′, lifting up the drilling tool to cause the directionalfollow-up tube having the tail tube 5′ for deflecting drill tool to moveupward and after removing the lift sub, sink them altogether into well.At the depth of deflecting drilling through the centralizer by means ofconventional drill pipe, proceed to perform level drilling through thetorque transmitted, by the flexible drill pipe 3, to the level drill bit21, with the directional follow-up tube to follow-up 4 at the same time.When the designed footage of 14 m is reached, stop drilling and reversefor haft a turn so that the quick couplings 9 and 9′ separate from eachother. Lift the drill pipe up to combine the convex and recessed facesof the convex left hand thread coupling 8 and the recessed left handthread bushing 8′ of tail tube. Turn forward drill pipe so that therecessed left hand thread bushing and the convex left hand threadcoupling separate from each other. Lift the drill pipe out of well andleave the directional follow-up tube 4 and the level rotary assembly 2in the level well hole and tail tube 5′ for level drill tool in thestraight interval. In drilling process, drilling fluid is conveyed in away of reverse circulation through the annular space between well casingand the drill pipe and returned it to ground through central holes ofthe drill bit and the drill pipe, ensuring thoroughly removing of rockcuttings and avoiding “sand sticking”.

Step 4, Finish well completion work after lead seal setting.

Example 2 Assembling of Various Parts of the Present Invention

(1) Level drilling footage is 45.0 m; length of the fixed flexible drillpipe is 45.0 m, each section of the flexible drill pipe being 150 mmlong. Inner balls are made of 40#Cr—Ni—Mo.

(2) The directional follow-up tube 4 is made of slotted seamless steeltube, width of slot being 4 mm and spacing between slots being 110 mm.There are 70 mm width of tube wall to be left at lower part of the tube,serving as rib.

Drilling Process:

At the designed drilling depth, a 1.3 m window has to be cut on casingwall. Bending degree of the flexible drill pipe is 18°/m and thedeflecting angle is 90°. For every 5.0 m of drilling footage, thecurvature radius R=5.0*4/(2p)=3.18 m, which is within the range ofultra-short radius deflecting process all the same.

The process for making other parts and technology of drilling are referto the Example 1.

Example 3 Assembling of Various Parts of the Present Invention

(1) Level drilling footage is 98.0 m; each section of the flexible drillpipe being 140 mm long, Length of the fixed flexible drill pipeinstalled is 98.0 m, Inner balls are made of 42#Cr—Mo.

(2) The width of slot of the directional follow-up tube 4 is 4 mm andspacing between slots being 105 mm. There are 60 mm width of tube wallto be left at lower part of the tube, serving as rib.

Drilling Process:

Bending degree of the flexible drill pipe is 22°/m and the deflectingangle is 90°. For every 4.1 m of drilling footage, the curvature radiusR=4.1*4/(2p)=2.61 m.

The process for making other parts and technology of drilling are referto the Example 1.

1. Tools of radial and level drilling and well completing underultra-short radius are involved with a deflecting drill tool and leveldrill tool; the deflecting drill tool consists of a deflecting rotaryassembly (1), flexible drill pipe (3), directional follow-up tube (4),tail tube (5) for deflecting drill tool, and drill pipe nipple joints(6); the level tool consists of a level rotary assembly (2), theflexible drill pipe (3), quick couplings (9, 9′), the directionalfollow-up tube (4), a tail tube (5′) for level drill tool, the drillpipe nipple joint (6), an adjusting nipple joint (7), a recessed lefthand thread bushing (8′), and convex left hand thread coupling (8) andcharacterized in that: a) the deflecting rotary assembly (1) has adeflecting drill bit (11) installed on front end of its central shaft(12), on which besides relevant centralizing bearing (14) and pressurebearing (16), have a collar (13) and felt washer assemblage (17), with atriangle backing block (15) outside of a casing (18); rear end of thedeflecting rotary assembly (1) is connected with the flexible drill pipe(3) by means of nuts and by way of main body of flexible drill pipe(36); the level rotary assembly (2) has a level drill bit (21) installedon front end of its horizontal shaft (22), the rear end of the levelrotary assembly (2) having an internal spline (39′) connected with thequick coupling (9), and a centralizing bearing (23) and the pressurebearing, collar and felt washer assemblage are set inside of a casing(25), a rectangle backing block (24) is set outside of the casing (25);b) the flexible drill pipe (3) is made up of several single sectionseach of which is 140˜150 mm long and consisting of five parts; at frontend of an inner ball (31) there is a cylindrical shaped tail with theexternal spline (39); and there is the internal spline (39′) on the mainbody of the flexible drill pipe (36); the external spline and internalspline are matched through the nut (32) tightening; a ball body of theinner ball (31), surrounded with steel balls, is located inside a ballbowl (33) and at front part of the main body of the flexible drill pipe(36); the ball bowl (33) and the main body of the flexible drill pipe(36) are threaded tight by covering (34); last section of the flexibledrill pipe is integrally united with the adjusting nipple joint (7)through the nut (32) tightening; c) the quick couplings (9,9′) matchmutually; the quick coupling (9) is united with a tail of the horizontalshaft (22) integrally through the nut (32) tightening; the quickcouplings (9,9′) have a central tube (93), the external spline andinternal spline respectively and also its gasket (91) and gland (92); d)the directional follow-up tube (4) is made of a slotted seamless steelpipe; over the slotted pipe (44), bending angle banking stops (42) areinstalled, with 6-8 mm thick and 70-75 wide, and cover plates aresituated above bending angle banking stops for restricting lateralmovement of bending angle banking stops; space between slots is 100-110mm, width of the slot is 3.5-4 mm and at lower part of the pipe therehas left a 50-70 mm width of pipe wall to serve as rib; e) there are twokinds of tail tubes, one is tail tube (5) for the deflecting drill tool,another is tail tube (5′) for the level drill tool; wherein a right handthread bushing (51) is connected to a straight tube (53) by means of aright hand thread coupling (52); recessed left hand thread bushing (8′)is connected to a straight tube (53′) by means of a left hand threadcoupling (8).
 2. The tools of radial and level drilling and wellcompleting under ultra-short radius according to the claim 1,characterized in that an included angle of 2°-3° is formed between thedeflecting drill bit (11) and the directional follow-up tube (4) in thesame bending direction due to the triangle backing block (15) installedon outside of the casing (18) of the deflecting rotary assembly (1); thecentral shaft (22) is raised by means of the rectangle backing block(24) installed on outside of the casing (25) of the level rotaryassembly (2), so that the level drill bit (21) may work in leveldirection.
 3. The tools of radial and level drilling and well completingunder ultra-short radius according to the claim 1, characterized in thatthe external spline (39) and internal spline (39′) and nuts are used forconnecting sections of the flexible drill pipe (3) and any singlesection of the flexible drill pipe (3) may bend 3°-6°; the flexibledrill pipe (3) may be rotated within the range of 360°, each meter ofthe flexible drill pipe (3) to bend is 18˜22°.
 4. Technologies of radialand level drilling and well completion under ultra-short radius,characterized in that: a) cut a 1.0-1.3 m window on a well pipe wall atdesigned depth by using a whip-stock and milling cone firstly; b)inclined drilling: to fix the deflecting rotary assembly (1) onto frontend of the directional follow-up tube (4) connected the tail tube (5)for deflecting drill tool; after putting the flexible drill pipe (3)into the directional follow-up tube (4) and connect the flexible drillpipe (3) with central shaft (12) of the deflecting rotary assembly, thento sink the assembled body into a well; under functioning of thewhip-stock, a drill bit moves out of the well pipe wall, from thewindow, to keep performing inclined drilling until designed footage isreached, the inclined drilling tool is lift then; c) level drilling: tofix the level rotary assembly (2) onto front end of the directionalfollow-up tube (4) connected the tail tube (5′) for level drill tool; toput the flexible drill pipe (3) having the quick coupling (9′) at itsfront end, into the directional follow-up tube (4), the adjusting nipplejoint (7) and the drill pipe are connected at a tail of the flexibledrill pipe (3) by using a patching of flexible drill pipe (38); afterbeing matched with each other, the convex left hand thread coupling (8)and the recessed left hand thread bushing (8′) are connected to theadjusting nipple joint (7) by way of screwing, then sink the assembledbody into well after connection by using the recessed left hand threadbushing (8′) and the convex left hand thread coupling (8); the flexibledrill pipe (3) transmits torque to the level drill bit (21) and drivesit to perform level drilling, the directional follow-up tube (4) followsup until designed footage is reached; upon ending of drilling work,remove the quick couplings (9,9′) by reversing it for half a turn andthen lift the flexible drill pipe to such an extent that the convex lefthand thread coupling (8) is lifted to the recessed left hand bushing(8′) of tail tube; turn the drill pipe forward so that the recessed lefthand thread bushing (8′) is separated from the left hand thread coupling(8); lift the flexible drill pipe out of the well and leave thedirectional follow-up tube (4) and the level rotary assembly (2) inlevel interval and the tail tube (5′) for level drill tool in straighthole; d) finishing well completion work after lead seal setting.
 5. Thetechnologies of radial and level drilling and well completion underultra-short radius according to the claim 4, characterized in thatdrilling fluid is conveyed in drilling process, through the annularspace formed between the well pipe wall and the flexible drill pipe andthen is returned to ground along a drill bit hole and a central hole offlexible drill pipe (3), namely, drilling fluid is conveyed in away ofreverse circulation; when designed drilling depth is reached, theflexible drill pipe (3) has to be separated from the level rotaryassembly (2) via the quick coupling (9,9′); to lift the flexible drillpipe (3) to such an extent that the convex left hand coupling (8) is upto the recessed left hand bushing (8′) of the tail tube; turn theflexible drill pipe forward so that the recessed left hand threadbushing (8′) is separated from the convex left hand thread coupling (8);then lift the flexible drill pipe out of well and leave the directionalfollow-up tube (4) and the level rotary assembly (2) in the levelinterval and tail tube (5′) for level drill tool in the straight hole;finally, accomplish the work of well completion after lead seal setting.